Next generation wireless systems use a wideband technology that allows for simultaneously transmitting multiple transmit signals, corresponding to different baseband signals, to one or more base stations over a plurality of channels. In some mobile communication devices, this requires transmitting the multiple transmit signals using a single power amplifier. Envelope tracking technology exists to enable the power amplifier to more efficiently transmit a single radio frequency (RF) transmit signal. This efficiency is had by generating a power supply voltage to the power amplifier that tracks the envelope of the single transmit signal. However, the current envelope tracking schemes prove insufficient where a single power amplifier is used to transmit multiple transmit signals.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention. In addition, the description and drawings do not necessarily require the order illustrated. It will be further appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.